Here’s a question. Is it better for the marine environment to (A) build a marina basin with a concrete floatingdock marina, or (B) leave the bay, riverside or estuary with no development at all? Years ago the answer was obviously (B). No longer.
“Marinas made of carbonates are artificial reefs,” said Todd Turrell, principal at Turrell, Hall & Associates, an marine and environmental consulting firm in Naples, Florida. “Concrete docks, piles, bulkheads and riprap are habitat. They’re colonized by bivalves, tunicates and other filter feeders that remove particulates and pollutants from the water. That allows sunlight to penetrate the water column so photosynthesis can take place, add oxygen to the water and promote plant growth. If your marina has adequate flushing, there is a good chance that the water is as clean as before it was built. Of course, there can be a negative impact from boats in a marina, but that is typically minor compared with the benefits to the ecology.”
Carbonate-Structure Habitat
Turrell’s firm was commissioned by Bellingham Marine to perform a detailed study of the effects of introducing a concrete floating dock marina into the environment and to identify the types and quantities of marine life that colonize such a structure. The study was conducted at Regatta Marina in Naples, Florida. Apart from the extensive list of species found, the study verified the overwhelming benefits to the environment of providing habitat with concrete structures. In the case studied, the marina replaced a barren mud bottom and a seawall. Turrell has observed this throughout his travels. “In the Florida Keys, some marinas have vase sponges two feet long and 18 inches across attached to the docks with lobsters living inside. You’ll find crabs and fish grazing on the algae, a rich marine ecosystem. Developments like these can make the environment better than before they went in, again, subject to impacts of boats in the marina. We drop riprap in the ocean to create an artificial reef. A marina creates a similar habitat.”
Turrell said that one of the main threats to the environment today is CCA (copper, chromium and arsenic) treated piling. “We’ve solved that problem by encasing them in plastic. The plastic sleeve makes an area around the pile anoxic so marine organisms no longer destroy the wood and the CCA is contained. The pile can then last indefinitely. Plastic sleeves are required by code so CCA is no longer a problem.”
“Water quality has three main components,” Turrell said, “clarity, nutrients and dissolved oxygen. A project I consulted on in the Bahamas illustrates the point. It was an estuary with poor circulation and stunted mangroves. Once improvements were in place, the ecosystem came to life. The presence of a development increased circulation and oxygen levels in the water. The mangroves are much healthier than before.”
These changes took time, effort, commitment and learning. We have a lot to be proud of as an industry. As we interact with regulators, permitting agencies and the public at large, especially environmental groups who oppose development, keep this in mind: we are the good guys.
It wasn’t always so. Fifty years ago San Pedro harbor in the Port of Los Angeles, then as now, was alive with shipping and industry—but dead environmentally. Chris Crafts moored to the creosote-soaked fixed-timber docks had bottoms with life-killing TBT or copper-based antifouling paint. The water was turbid, dark, foul and mostly lifeless. Contaminated industrial waste was routinely piped into the harbor. Fuel spills got little notice or attention. Floating trash and dying seaweed collected in the corners of piers and marinas. In the upper reaches of the Dominguez Channel Estuary, the water was anoxic and devoid of life.
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